An ink-jet recording device records an image on a recording sheet being conveyed by ejecting ink droplets to the recording sheet. The ink is generally reserved in advance in a cartridge type ink tank (or an ink cartridge), and the ink is fed from the ink cartridge to a recording head. As the residual of the ink reserved decreases, the ink cartridge has to be replaced by new one (see JP-A-11-348303, JP-A-10-109427, JP-A-2004-345246, JP-A-2005-219416, and JP-A-2005-96446, for example).
Generally, the ink cartridge is housed and held in a case, and this case is arranged in the ink-jet recording device. Ink-jet recording devices can be categorized into the so-called “on-carriage type” and “off-carriage type” according to the position of arrangement of the ink cartridge. In the on-carriage type, the ink cartridge is mounted on a carriage, which can be reciprocated to cross the direction to convey the recording sheet and which carries the recording head. In other words, the aforementioned case is mounted on the carriage, and the ink is fed from the ink cartridge housed and held in that case to the recording head. In the off-carriage type, on the other hand, the case is disposed somewhere in the ink-jet recording device excepting the carriage, and the ink cartridge is housed and held in that case. In other words, the ink cartridge and the case are constituted in advance into a unit, and this unit is assembled in somewhere in the ink-jet recording device. As a result, the ink is fed from the case housing and holding the ink cartridge to the recording head through an ink supply pipe. This unit is called a “refill unit”. In this refill unit, an ink supply needle is arranged in a bottom of the case and is inserted into the ink cartridge when the ink cartridge is housed in the case. As a result, the ink in the ink cartridge is fed to the recording head through the ink supply needle and ink supply pipe.